ByteStream.js

ByteStream class

ByteStream class is the major class for all others. It provides many useful function for making search for patterns and data transformation. Optimized for fast as possible data processing.

Method	Description
clear	Clear existing stream
fromArrayBuffer	Initialize "Stream" object from existing "ArrayBuffer"
fromUint8Array	Initialize "Stream" object from existing "Uint8Array"
fromString	Initialize "Stream" object from existing string
toString	Represent "Stream" object content as a string
fromHexString	Initialize "Stream" object from existing hexdecimal string
toHexString	Represent "Stream" object content as a hexdecimal string
copy	Return copy of existing "Stream"
slice	Return slice of existing "Stream"
realloc	Change size of existing "Stream"
append	Append a new "Stream" content to the current "Stream"
insert	Insert "Stream" content to the current "Stream" at specific position
isEqual	Check that two "Stream" objects has equal content
isEqualView	Check that current "Stream" objects has equal content with input "Uint8Array"
findPattern	Find any byte pattern in "Stream"
findFirstIn	Find first position of any pattern from input array
findAllIn	Find all positions of any pattern from input array
findAllPatternIn	Find all positions of a pattern
findFirstNotIn	Find first position of data, not included in patterns from input array
findAllNotIn	Find all positions of data, not included in patterns from input array
findFirstSequence	Find position of a sequence of any patterns from input array
findAllSequences	Find all positions of a sequence of any patterns from input array
findPairedPatterns	Find all paired patterns in the stream
findPairedArrays	Find all paired patterns in the stream
replacePattern	Replace one patter with other
skipPatterns	Skip any pattern from input array
skipNotPatterns	Skip any pattern not from input array

SeqStream class

SeqStream class is the aux class for sequential reading/writing data from/to ByteStream underline class.

Method	Description
resetPosition	Reset current position of the "SeqStream"
findPattern	Find any byte pattern in "ByteStream"
findFirstIn	Find first position of any pattern from input array
findAllIn	Find all positions of any pattern from input array
findFirstNotIn	Find first position of data, not included in patterns from input array
findAllNotIn	Find all positions of data, not included in patterns from input array
findFirstSequence	Find position of a sequence of any patterns from input array
findAllSequences	Find position of a sequence of any patterns from input array
findPairedPatterns	Find all paired patterns in the stream
findPairedArrays	Find all paired patterns in the stream
replacePattern	Replace one patter with other
skipPatterns	Skip of any pattern from input array
skipNotPatterns	Skip of any pattern from input array
append	Append a new "Stream" content to the current "Stream"
appendView	Append a "view" content to the current "Stream"
appendChar	Append a new char to the current "Stream"
getBlock	Get a block of data
getUint32	Get 4-byte unsigned integer value

BitStream class

Main purpose of the BitStream is manipulating of each bit inside any ByteStream data.

Method	Description
clear	Clear existing stream
fromByteStream	Initialize "BitStream" by data from existing "ByteStream"
fromArrayBuffer	Initialize "BitStream" object from existing "ArrayBuffer"
fromUint8Array	Initialize "BitStream" object from existing "Uint8Array"
fromString	Initialize "BitStream" object from existing bit string
toString	Represent "BitStream" object content as a string
shiftRight	Shift entire "BitStream" value right to number of bits
shiftLeft	Shift entire "BitStream" value left to number of bits
slice	Return slice of existing "BitStream"
copy	Return copy of existing "BitStream"
shrink	Shrink unnecessary bytes in current stream accordingly to "bitsCount" value
reverseBytes	Reverse bits order in each byte in the stream
reverseValue	Reverse all bits in entire "BitStream"
getNumberValue	Trying to represent entire "BitStream" as an unsigned integer
findPattern	Find any bit pattern in "BitStream"
findFirstIn	Find first position of any pattern from input array
findAllIn	Find all positions of any pattern from input array
findAllPatternIn	Find all positions of a pattern
findFirstNotIn	Find first position of data, not included in patterns from input array
findAllNotIn	Find all positions of data, not included in patterns from input array
findFirstSequence	Find position of a sequence of any patterns from input array
findAllSequences	Find position of a sequence of any patterns from input array
findPairedPatterns	Find all paired patterns in the stream
findPairedArrays	Find all paired patterns in the stream
replacePattern	Replace one pattern with other
skipPatterns	Skip any pattern from input array
skipNotPatterns	Skip any pattern not from input array
append	Append a new "BitStream" content to the current "BitStream"

SeqBitStream class

SeqBitStream class is the aux class for sequential reading/writing data from/to BitStream underline class.

Method	Description
getBits	Get next "length" bits from the stream
getBitsString	Get string representation for the next "length" bits from the stream
getBitsReversedValue	Get number value representation of the next "length" bits from the stream, preliminary reversed
toString	Represent remaining bits in "BitStream" as a string

Wildcard byte patterns

The ByteStream class provides an option to use wildcard byte patterns. These are useful in searching for magic bytes in a file format.

Example of using wildcard byte patterns:

1let wildcard = "?".charCodeAt(0);
2let searchPattern = new ByteStream({
3	// set wildcard byte value
4	wildcard: wildcard,
5	// set search pattern with wildcard bytes ("s??e ")
6	view: new Uint8Array([0x73, wildcard, wildcard, 0x65, 0x20])
7});
8let dataPattern = new ByteStream({ data: 'some random data 0x00 0x00 0x01 0x45' });
9dataPattern.findPattern(searchPattern); // find search pattern in data pattern

parseByteMap functionality

The parseByteMap function is intended to parse and check byte streams with determined structure.

Example of map used as a kind of template. Exactly this map is using for parsing PDF xref table:

1let map = [
2	{
3		type: "string",
4		name: "type",
5		minlength: 1,
6		maxlength: 1,
7		func: function(array){
8			let result = {
9				status: (-1),
10				length: 1
11			};
12
13			switch(array[0])
14			{
15				case 0x6E: // "n"
16					result.value = "n";
17					break;
18				case 0x66: // "f"
19					result.value = "f";
20					break;
21				default:
22					return result;
23			}
24
25			result.status = 1;
26
27			return result;
28		}
29	},
30	{
31		type: "check",
32		minlength: 1,
33		maxlength: 2,
34		func: function(array){
35			let position = (-1);
36
37			if(array[0] == 0x0A)
38				position = 1;
39			if(array[1] == 0x0A)
40				position = 2;
41
42			return {
43				status: (position > 0) ? 1 : (-1),
44				length: position
45			};
46		}
47	}
48];

License

Copyright (c) 2016-2022, Peculiar Ventures All rights reserved.

Author 2016-2018 Yury Strozhevsky.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.